121661993 has 2 divisors, whose sum is σ = 121661994. Its totient is φ = 121661992.

The previous prime is 121661987. The next prime is 121662043. The reversal of 121661993 is 399166121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 121066009 + 595984 = 11003^2 + 772^2 .

It is a cyclic number.

It is not a de Polignac number, because 121661993 - 2⁶ = 121661929 is a prime.

It is not a weakly prime, because it can be changed into another prime (121661923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60830996 + 60830997.

It is an arithmetic number, because the mean of its divisors is an integer number (60830997).

Almost surely, 2^121661993 is an apocalyptic number.

It is an amenable number.

121661993 is a deficient number, since it is larger than the sum of its proper divisors (1).

121661993 is an equidigital number, since it uses as much as digits as its factorization.

121661993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17496, while the sum is 38.

The square root of 121661993 is about 11030.0495465796. The cubic root of 121661993 is about 495.5091085517.

The spelling of 121661993 in words is "one hundred twenty-one million, six hundred sixty-one thousand, nine hundred ninety-three".